What is Private Label?
Private label refers to a merchant selling their own branded products on Amazon; a PL seller can put brand restrictions in place so that other sellers cannot sell it.
If you attempt to sell a PL product, Amazon may block your listing and suspend your account; to become authorized to sell a product, you should contact the manufacturer/seller that owns the brand.
In SAS you'll be alerted to this in the Quick Info and Alerts panel: